<template>
  <div class="file-upload">
    <div class="upload-area"
      :class="{'is-dragover': drag && isDragOver }"
      v-on="events"
    >
      <slot v-if="isUploading" name="loading">
        <button disabled>正在上传</button>
      </slot>
      <slot name="uploaded" v-else-if="lastFileData && lastFileData.loaded" :uploadedData="lastFileData.data">
        <button>点击上传</button>
      </slot>
      <slot v-else name="default">
        <button>点击上传</button>
      </slot> 
    </div>
    <input
      ref="fileInput"
      type="file"
      :style="{display: 'none'}"
      @change="handleFileChange"
    >
    <ul :class="`upload-list upload-list-${listType}`" v-if="showUploadList">
      <li :class="`uploaded-file upload-${file.status}`"
        v-for="file in filesList" 
        :key="file.uid">
        <img
          v-if="file.url && listType === 'picture'"
          class="upload-list-thumbnail"
          :src="file.url"
          :alt="file.name"
        >
        <span v-if="file.status === 'loading'" class="file-icon"><LoadingOutlined/></span>
        <span v-else class="file-icon"><FileOutlined/></span>
        <span class="filename">{{file.name}}</span>
        <span class="delete-icon" @click="removeFile(file.uid)"><DeleteOutlined/></span>
      </li>
    </ul> 
  </div>
</template>

<script lang="ts">
import { defineComponent, reactive, ref, computed, PropType } from 'vue'
import { DeleteOutlined, LoadingOutlined, FileOutlined } from '@ant-design/icons-vue'
import axios from 'axios'
import { v4 as uuidv4 } from 'uuid'
import { last } from 'lodash-es'

type UploadStaus = 'ready' | 'loading' | 'success' | 'error'
type FileListType = 'picture' | 'text' 
type CheckUpload = (file: File) => boolean | Promise<File>
export interface UploadFile {
    uid: string;
    size: number;
    name: string;
    status: UploadStaus;
    raw: File;
    resp?: any;
    url?: string;
}
export default defineComponent({
    components: {
        DeleteOutlined,
        LoadingOutlined,
        FileOutlined        
    },
    props: {
        action: {
            type: String,
            required: true
        },
        beforeUpload: {
            type: Function as PropType<CheckUpload>
        },
        drag: {
            type: Boolean,
            default: false    
        },
        autoUpload: {
            type: Boolean,
            default: true
        },
        listType: {
            type: String as PropType<FileListType>,
            defualt: 'text'
        },
        showUploadList: {
            type: Boolean,
            default: true
        }
    },
    emits: ['success', 'error', 'change'],
    setup(props, {emit}) {
        const fileInput =  ref<null | HTMLInputElement>(null)
        const filesList = ref<UploadFile[]>([])
        const isDragOver = ref(false)
        const isUploading = computed(() => {
            return filesList.value.some(file => file.status === 'loading')
        })
        const lastFileData = computed(() => {
            const lastFile = last(filesList.value)
            if(lastFile) {
                return {
                    loaded: lastFile.status === 'success',
                    data: lastFile.resp
                }
            }
            return false
        })
        const removeFile = (id: string) => {
            filesList.value = filesList.value.filter(file => file.uid !== id)
        }
        const triggerUpload = () => {
            if(fileInput.value) {
                fileInput.value.click()
            }
        }
        const postFile = (readyFile: UploadFile) => {
            const formDate = new FormData()
            formDate.append(readyFile.name, readyFile.raw)
            readyFile.status = 'loading'
            axios.post(props.action, formDate, {
                headers: {
                    'Content-Type': 'multipart/form-data'
                }
            }).then(resp => {
                readyFile.status = 'success'
                readyFile.resp = resp.data
                emit('success', { resp: resp.data, file: readyFile, list: filesList.value })
            }).catch((e: any) => {
                readyFile.status = 'error'
                emit('error', { error:e, file: readyFile, list: filesList.value })
            }).finally(() => {
                if(fileInput.value){
                    fileInput.value.value = ''
                }
            })
        }
        // addFileToList
        const addFileToList = (uploadedFile: File) => {
            const fileObj = reactive<UploadFile>({
                uid: uuidv4(),
                size: uploadedFile.size,
                name: uploadedFile.name,
                status: 'ready',
                raw: uploadedFile
            })
            if(props.listType === 'picture') {
                try {
                    fileObj.url = URL.createObjectURL(uploadedFile)
                } catch (err) {
                    console.error('upload File error', err)
                }
            }
            filesList.value.push(fileObj)
            if (props.autoUpload) {
                postFile(fileObj)
            }
        }

        const beforeUploadCheck = (files: null | FileList) => {
            if(files) {
                const uploadedFile = files[0]
                if(props.beforeUpload) {
                    const result = props.beforeUpload(uploadedFile)
                    if (result && result instanceof Promise) {
                        result.then(processedFile => {
                        if (processedFile instanceof File) {
                            addFileToList(processedFile)
                        } else {
                            throw new Error('beforeUpload Promise should return File object')
                        }
                        }).catch(e => {
                        console.error(e)
                        })
                    } else if (result === true) {
                        addFileToList(uploadedFile)
                    }
                } else {
                    addFileToList(uploadedFile)
                }

            }
        }

        const uploadFiles = () => {
            filesList.value.filter(file => file.status === 'ready').forEach(readyFile => postFile(readyFile))
        }
        let events: { [key: string]: (e: any) => void } = {
            'click': triggerUpload
        }
        const handleFileChange = (e: Event) => {
            const target = e.target as HTMLInputElement
            beforeUploadCheck(target.files)
        }
        const handleDrag = (e: DragEvent, over: boolean) => {
            e.preventDefault()
            isDragOver.value = over
        }
        const handleDrop = (e: DragEvent) => {
            e.preventDefault()
            isDragOver.value = false
            if (e.dataTransfer) {
                beforeUploadCheck(e.dataTransfer.files)
            }
        }
        if (props.drag) {
            events = {
                ...events,
                'dragover': (e: DragEvent) => { handleDrag(e, true)},
                'dragleave': (e: DragEvent) => { handleDrag(e, false)},
                'drop': handleDrop
            }
        }
        return {
            fileInput,
            handleFileChange,
            isUploading,
            filesList,
            removeFile,
            lastFileData,
            isDragOver,
            events,
            uploadFiles
        }


    },
})
</script>
<style scoped >
.upload-list {
  margin: 0;
  padding: 0;
  list-style-type: none;  
}
.upload-list li {
  transition: all .5s cubic-bezier(.55,0,.1,1);
  font-size: 14px;
  line-height: 1.8;
  margin-top: 5px;
  box-sizing: border-box;
  border-radius: 4px;
  min-width: 200px;
  position: relative;

}
  .upload-list :first-child {
    margin-top: 10px;
  }
    .upload-list-thumbnail {
    vertical-align: middle;
    display: inline-block;
    width: 70px;
    height: 70px;
    position: relative;
    z-index: 1;
    background-color: #fff;
    object-fit: cover;
  }
  .file-icon svg {
      margin-right: 5px;
      color: rgba(0, 0, 0, 0.45);
    }
  
  .filename {
    margin-left: 5px;
    margin-right: 40px;
  }
  .upload-list .upload-error {
    color: #f5222d;
  }
   .upload-list .upload-error   svg {
      color: #f5222d;
    }
  .file-status {
    display: block;
    position: absolute;
    right: 5px;
    top: 0;
    line-height: inherit;
  }
  .delete-icon {
    display: none;
    position: absolute;
    right: 7px;
    top: 0;
    line-height: inherit;
    cursor: pointer;
  }
  upload-list :hover {
    background-color: #efefef;
  }
    .file-status {
        display: none;
    }
    .delete-icon {
        display: block;
    }
</style>